If you have a decent PC, go for it. Medium is about the same as the console versions, so if you can run it nicely on medium then that's basically equal to the console versions. Except you can use mods, the console, tweaks etc.
If your computer isn't up to scratch however, don't bother. Nothing destroys immersion like trying to play a game at lowest settings with 10fps.
Actually the console versions run a mixture of medium and low. Mostly low settings though.
PC for certain. I actually got both and the ps3 is a simplified version imo(like Civ, FO, etc) and the ps3 version isnt bad so much as it is just a simpler version. The PC has ALOT more built-in replayability purely because of the modding community and what they bring to a game. The CK isn't even out yet and there are hundreds (thousands, maybe? by now) of mods out there that greatly enhance the game. And then when you consider how much better the game looks on PC(as well as all those mods out there making it look even better.....) well, it makes the PC the clear winner. The only thing is, as some have mentioned, how good of a machine you have. It does not mean you can't play the game on a lower end machine(as long as you meet the minimums of course), you just won't be able to blast along like a powerful gaming PC can.
I have a very nice machine with dual video quad core yadda yadda myself, and it just smokes! Great game!
I'm jealous

.
I have a nice machine with dual video cards but turning on Crossfire actually reduces my FPS by a ton, even on latest preview driver + latest CAP.
I do get 40+ FPS outdoors / cities with one card though, so not too bad. That's ultra + tweaks too, ugristoload=9.